Translucent soap bar composition and method of making the same

ABSTRACT

A soap bar composition includes a soap mixture, a polyalkylene glycol, at least one of glycerin and sorbitol, water; and optionally, free fatty acid. The soap bar composition exhibits translucent properties.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional PatentApplication, Serial No. 60/407,386 entitled “Translucent Soap BarComposition,” filed on Aug. 30, 2002, which is incorporated by referenceherein.

FIELD OF INVENTION

[0002] The present invention relates generally to soap compositions andtheir method of manufacture, and more particularly to soap compositionsthat exhibit translucent properties.

BACKGROUND OF THE INVENTION

[0003] Translucent soap bars are popular among consumers for theiraesthetic appeal and their connotation of purity and high moisturecontent. Generally, a translucent bar soap is composed largely of onesingle homogeneous crystalline phase known as the “beta phase.” The betaphase is one of four known crystalline phases of soap and impartstranslucence, generally due to the small size of the soap crystals,which are too small to diffract light.

[0004] As used herein, the meaning of “translucent” is that which isgenerally employed and is generally in accordance with the usualdictionary definition. For example, a translucent soap is one thatallows light to pass through it but the light may be so scattered, as bya small proportion of crystals or insolubles, such that it will not bepossible to clearly identify objects behind the translucent soap.Furthermore, translucent soaps may include clear, colorless, and coloredtransparent soaps.

[0005] As with conventional, opaque soaps, it is popular to includeadditives, such as antibacterial agents, fragrance, vitamins andcolorants, to translucent soaps bars to provide other beneficialcharacteristics. However, these additional ingredients may impairtranslucency of the final product. In such cases, it may be necessaryduring manufacturing to run the mix of ingredients through refining andmilling processes multiple times before an acceptable translucency isachieved. Such additional processing increases manufacturing time,energy and manpower, thus increasing product costs and decreasingthroughput.

[0006] Accordingly, there is a need for soap bar compositions thatexhibit satisfactory translucency without undesirable processing. Thepresent invention addresses this long felt, yet unresolved need.

SUMMARY OF THE INVENTION

[0007] This summary of the invention section is intended to introducethe reader to aspects of the invention. Particular aspects of theinvention are pointed out in other sections herein below, and theinvention is set forth in the appended claims which alone demarcate itsscope.

[0008] In accordance with an exemplary embodiment of the presentinvention, a soap bar composition is provided. The soap bar compositionincludes a soap mixture, a polyalkylene glycol, at least one of glycerinand/or sorbitol, water, and optionally, free fatty acid. The soap barcomposition exhibits translucent properties.

[0009] In accordance with a further exemplary embodiment of the presentinvention, a translucent soap bar is provided. The soap bar includes, byweight, about 65 to about 80% of a soap mixture, about 0.5 to about 5.0%of a polyethylene glycol having a molecular weight in the range of about300 to about 800, about 4.5 to about 8.5% glycerin, about 12 to about16% water, and, optionally, about 1.5 to about 3.0% of a free fattyacid.

[0010] In accordance with another exemplary embodiment of the presentinvention, a process for making soap bars is provided. The soap barsexhibit translucent properties and include a soap mixture, apolyethylene glycol having a molecular weight in the range of about300-800, glycerin, water, and, optionally, a free fatty acid. Theprocess includes saponifying oils with a caustic solution to form a soapmixture, optionally neutralizing unreacted caustic solution with thefree fatty acid, and spray drying the soap mixture and ultimatelyforming soap pellets. Polyethylene glycol is added to the soap pelletsto aid processing, and the mixture is then subjected to plodding,roll-milling and extrusion to form a soap ribbon. The soap ribbon is cutand stamped to form soap bars.

DETAILED DESCRIPTION

[0011] The following description is of exemplary embodiments only and isnot intended to limit the scope, applicability or configuration of theinvention in any way. Rather, the following description provides aconvenient illustration for implementing various exemplary embodimentsof the invention. Various changes to the described embodiments may bemade without departing from the scope of the invention as set forth inthe appended claims.

[0012] In one exemplary embodiment of the present invention, thetranslucent soap bar composition comprises a soap mixture. As usedherein, the term “soap” is defined as any water-soluble salt of thosefatty acids that contain about 8 or more carbon atoms. In an exemplaryembodiment of the present invention, the soap mixture comprises at leastone of sodium tallowate, sodium palmitate, sodium stearate and sodiumpalm kernelate, salts of fatty acids having alkyl chain lengths with 12to 18 carbons. In a preferred embodiment of the invention, the soapmixture suitably comprises a blend of sodium tallowate, sodiumpalmitate, sodium stearate and sodium palm kernelate. It will beappreciated, however, that other fats and oils from which soaps may beproduced can be employed, such as babassu oil, soybean oil, cottonseedoil, rapeseed oil or other comparable vegetable product, whale or fishoils and lards, and the like. Various other animal fats and oils mayalso be employed to produce soaps similar totallow/palmitate/stearate/palm kernelate soaps mentioned above.

[0013] Generally, fatty acids with alkyl chains having 12 to 18 carbonsare most desirable for soap production, as shorter alkyl chains may notproduce the desired soap properties. Fatty acids with chain lengthshaving 20 carbons or more have very little solubility and may impedelathering.

[0014] In one embodiment of the translucent soap bar composition of thepresent invention, the soap mixture comprises about 65 to about 80% byweight of the translucent soap composition. In a preferred embodiment ofthe invention, the soap mixture comprises about 70 to about 75% byweight of the translucent soap composition. It will be appreciated,however, that any suitable amount of the soap mixture may be used toimpart a cleaning benefit to the translucent soap bar. Generally, thesoap mixture comprises more than about 60% by weight of the translucentsoap composition, and more preferably more than about 70% by weight ofthe translucent soap composition.

[0015] In another exemplary embodiment of the present invention, sodiumtallowate, sodium palmitate and sodium stearate comprises about 80 toabout 90% by weight of the soap mixture and sodium palm kernelatecomprises about 10 to about 20% by weight of the soap mixture. In apreferred embodiment, sodium tallowate, sodium palmitate and sodiumstearate comprise on the order of about 85% of the soap mixture andsodium palm kernelate comprises on the order of about 15% of the soapmixture.

[0016] Preferably, the translucent soap composition of the presentinvention also comprises glycerin, sorbitol, or a mixture of glycerinand/or sorbitol. In one exemplary embodiment of the present invention,the translucent soap bar composition comprises about 4.5 to about 8.5%by weight glycerin. In a preferred embodiment, the translucent soapcomposition comprises about 6.0 to about 8.0% by weight glycerin.

[0017] Preferably, the transparent soap composition also compriseswater. In one exemplary embodiment of the present invention, thetransparent soap composition comprises about 10 to about 20% by weightwater. In a preferred embodiment of the present invention, thetransparent soap composition comprises about 12 to about 16% by weightwater.

[0018] The translucent soap bar composition also comprises apolyalkylene glycol, which may include polyethylene glycols andpolypropylene glycols, having a relatively low molecular weight. Theinventors have found that use of a polyalkylene glycol having arelatively low molecular weight enhances the translucent properties ofthe soap bar composition of the present invention. In one embodiment ofthe invention, the translucent soap bar composition comprisespolyethylene glycol having a molecular weight in the range of about 300to about 800. In a preferred embodiment of the invention, thetranslucent soap bar composition comprises polyethylene glycol having amolecular weight of 400, which is typically sold commercially as“PEG-8”. In another exemplary embodiment of the present invention, thetranslucent soap bar composition comprises about 0.5 to about 5.0% byweight polyethylene glycol. In a preferred embodiment of the invention,the translucent soap composition comprises about 1.0 to about 2.0% byweight polyalkylene glycol.

[0019] In another exemplary embodiment of the invention, the translucentsoap bar composition may comprise free fatty acid. The free fatty acidsgenerally may have alkyl chain lengths with 8 to 22 carbons, butpreferably 12 to 18 carbons. An example of a suitable free fatty acidfor use in the translucent soap composition of the present invention islauric acid, although it will be appreciated that any suitable freefatty acid having an alkyl chain length of 8 to 22 carbon atoms may beused.

[0020] In another exemplary embodiment of the present invention, thetranslucent soap bar composition may comprise one or more otherconventional processing aids and conventional additives, includingorganic and inorganic salts, chelating agents, vitamins, dyes,moisturizers, antibacterial agents, preservatives, antioxidants,conditioners, exfoliants, emollients, and the like.

[0021] A process for making translucent soap bars in accordance with oneexemplary embodiment of the present invention will now be described. Asoap mixture may be manufactured by saponifying suitable raw oils, suchas, for example, tallow, palm oil, stearin oil and palm kernel oil, witha caustic solution, such as sodium hydroxide, to form a “neat soap.” ThepH of the neat soap may be alkaline when produced and can be suitablyadjusted by the addition of an organic acid, such as citric acid. Freefatty acid may also be added to the neat soap to neutralize anyundesirable excess caustic solution and to enhance the lathercharacteristics of the resulting soap. Optionally, at this stage of theprocess, preservative agents, chelating agents, and inorganic and/ororganic salts may also be added. The neat soap may then be spray driedto reduce the moisture content of the soap, yielding soap pellets. Inone embodiment of the invention, the water content is reduced to about16 to about 19% by weight of the soap pellets.

[0022] Pre-mixes then may be formulated. The PEG-8 and colorants may becombined into a first pre-mix using, for example, a slurry tankagitator. Perfume and other active ingredients, such as an antibacterialagent, skin controlling agents, and other additives may be combined inthe second pre-mix.

[0023] The soap pellets may then be transferred to an amalgamator wherethey are coated with the ingredients of the three pre-mixes. The threepre-mixes may be added to the soap pellets sequentially or in unison.The coated pellets may then be double refined through a twin-screwformulation plodder and transported to a four-roll/double-pass mill anda first duplex plodder that pelletizes the soap. The refined formulatedpellets may then be transported to the top hopper of a final duplexplodder at which point a recycle stream from a soap press, describedbelow, is introduced. The mix may be combined through the top hopper,preferably with screens and compaction plates removed. A lower vacuumplodder then may extrude the soap into a ribbon that may be cut intoslugs. The slugs may be stamped into finished bars using an automaticsoap press, from which the recycle stream described above is produced.

[0024] While the above process describes one embodiment formanufacturing the translucent soap bar composition of the presentinvention, it will be appreciated that the translucent soap barcomposition of the present invention is not limited to the method ofmanufacture described above, but can be manufactured using any suitableprocess. For example, the soap may be manufactured in a batch processwhere all the ingredients are combined in situ and processed to refinethe crystallinity of the mixture to produce a translucent soap barcomposition. In another exemplary embodiment, the translucent soapcomposition may be subjected to additional plodding and/or milling tofurther enhance the translucency of the resulting composition.

[0025] An exemplary embodiment of the translucent soap bar compositionof the present invention, with each of the components set forth inweight percent of the total soap bar composition, is as follows:Component wt. % soap (sodium tallowate, sodium palm 72.0129 kernelate,sodium palmitate and sodium stearate) water 14.3700 glycerin 7.6060lauric acid 2.1076 fragrance 1.5000 polyethylene glycol (PEG-8) 1.4994chelating agent (pentasodium pentetate) 0.2108 chelating agent(tetrasodium etidronate) 0.2108 antibacterial agent (triclosan) 0.1999sodium chloride 0.1341 vitamin additives 0.1000 citric acid 0.0479 dye(red 4) 0.0003 dye (yellow 5) 0.0003 Total 100.00

[0026] While the above example illustrates a soap composition comprisinga soap mixture of sodium tallowate, sodium palm kernelate, sodiumpalmitate and sodium stearate, free fatty acid of lauric acid, and apolyalkylene glycol of PEG-8, it will be appreciated that any othersuitable soap mixture, free fatty acid and polyalkylene glycol may beused and may be present in any suitable amount. It will further beappreciated that although an example of a soap composition comprisingglycerin is illustrated above, sorbitol or a sorbitol and glycerinmixture could also be used. Similarly, while the above exampleillustrates use of chelating agents, dyes, fragrance, bacterial agentand vitamins, it will be understood that any other conventional,suitable additive or combination of additives, present in any suitableproportion, may be used. Further, it will be appreciated that any suchadditives may be absent from the translucent soap bar compositionaltogether.

[0027] To evidence the performance characteristics of variousformulations of the translucent soap bar compositions according to thepresent invention, tests were conducted to determine the difference intranslucency between soap compositions with a polyalkylene glycol andthose without. Ten peach-colored translucent soap bars, Sample A, weremanufactured using the formulation and process described above, eachsoap bar comprising about 1.5% PEG-8. Ten other peach-coloredtranslucent soap bars, Sample B, were manufactured using the sameformulation and process as those of the soap bars of Sample A, exceptthe soap bars of Sample B did not contain any polyalkylene glycol.

[0028] Similarly, ten teal-colored translucent soap bars, Sample C, weremanufactured using a formulation and process similar to those describedabove, each soap bar comprising about 1.5% PEG-8, although variations indye color to accommodate teal-colored bars were implemented. Ten otherteal-colored translucent soap bars, Sample D, were manufactured usingthe same formulation and process as those of the soap bars of Sample C,except that the soap bars of Sample D did not contain any polyalkyleneglycol.

[0029] Opacity measurements were taken on a Hunter Lab Color Quest IIcolorimeter capable of measuring the reflectance of light through asample bar, first against a white background and then against a blackbackground. Opacity of the soap bars was calculated according to theequation:${\% \quad {Opacity}} = {\lbrack \frac{Y_{black\_ background}}{Y_{white\_ background}} \rbrack \times 100}$

[0030] where Y_(black) _(—) _(background) is the reflectance value of asoap bar against a black background and Y_(white) _(—) _(background) isthe reflectance value of the soap bar against a white background. Asreflectance increases (i.e., as translucency improves), Y_(white) _(—)_(background) increases and Y_(black) _(—) _(background) decreases.Thus, as opacity decreases, translucency increases.

[0031] Table 1 illustrates the increase in translucency between SampleA, the peach-colored soap bars without PEG-8, and Sample B, thepeach-colored soap bars with PEG-8: TABLE 1 Sample A Sample B % Increase(Peach) Opacity (Peach) Opacity Translucency Bar 1  94.09 Bar 1  79.0416.00 Bar 2  93.18 Bar 2  78.16 16.12 Bar 3  94.85 Bar 3  78.43 17.31Bar 4  94.45 Bar 4  79.68 15.64 Bar 5  94.82 Bar 5  82.53 12.96 Bar 6 95.87 Bar 6  79.00 17.60 Bar 7  93.52 Bar 7  81.70 12.64 Bar 8  95.15Bar 8  77.72 18.32 Bar 9  95.15 Bar 9  78.45 17.55 Bar 10 93.77 Bar 1077.83 17.00 Overall 16.11% Average:

[0032] Similarly, Table 2 illustrates the increase in translucencybetween Sample C, the teal-colored soap bars without PEG-8, and SampleD, the teal-colored soap bars with PEG-8: TABLE 2 Sample C Sample D %Increase (Teal) Opacity (Teal) Opacity Translucency Bar 1  97.12 Bar 1 84.12 13.39 Bar 2  96.69 Bar 2  86.09 10.96 Bar 3  96.49 Bar 3  84.9711.94 Bar 4  97.26 Bar 4  83.43 14.22 Bar 5  96.91 Bar 5  87.57 9.64 Bar6  97.28 Bar 6  86.05 11.54 Bar 7  96.66 Bar 7  83.14 13.99 Bar 8  96.57Bar 8  86.43 10.50 Bar 9  97.60 Bar 9  86.34 11.54 Bar 10 96.69 Bar 1084.88 12.21 Overall 11.99% Average:

[0033] The above results illustrate that the addition of a polyalkyleneglycol in an amount as small as 1.5% by weight of the soap compositionincreased the translucency of the soap bar composition to an extentnoticeable to a consumer. For the peach-colored soap bars, translucencyincreased an average of about 16.11%. For the teal-colored soap bars,translucency increased an average of about 12%.

[0034] As should now be appreciated, the translucent soap barcomposition, in accordance with the various embodiments of the presentinvention evidences translucent properties while comprising a soapmixture, glycerin, water and a relatively small amount of a polyalkyleneglycol having a low molecular weight. It will be appreciated inaccordance with principles of the present invention, various otheradditives can be used without significantly affecting the translucentproperties of the soap composition.

[0035] In the foregoing specification, the invention has been describedwith reference to specific embodiments. However, one of ordinary skillin the art appreciates that various modifications and changes can bemade without departing from the scope of the present invention as setforth in the claims below. Accordingly, the specification is to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope of thepresent invention.

[0036] Benefits, other advantages, and solutions to the problems havebeen described above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any element(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature or element of any or all the claims. As used herein, the terms“comprises,” “comprising,” or any other variation thereof, are intendedto cover a non-exclusive inclusion, such that a process, method,article, or apparatus that comprises a list of elements does not includeonly those elements but may include other elements not expressly listedor inherent to such process, method, article, or apparatus.

We claim:
 1. A soap bar composition comprising: a soap mixture; apolyalkylene glycol; at least one of glycerin and sorbitol; water; andoptionally, free fatty acid, wherein said soap bar composition exhibitstranslucent properties.
 2. The soap bar composition of claim 1, saidsoap mixture comprising a blend of soaps having alkyl chain lengths with12 to 18 carbon atoms.
 3. The soap bar composition of claim 1, said soapmixture comprising at least one of sodium tallowate, sodium palmitate,sodium stearate and sodium palm kernelate.
 4. The soap bar compositionof claim 1, the soap bar composition comprising about 65 to about 85weight percent soap mixture.
 5. The soap bar composition of claim 4, thesoap bar composition comprising about 70 to about 75 weight percent soapmixture.
 6. The soap bar composition of claim 1, the soap barcomposition comprising about 4.5 to about 8.5 weight percent glycerin.7. The soap bar composition of claim 6, the soap bar compositioncomprising about 6.0 to about 8.0 weight percent glycerin.
 8. The soapbar composition of claim 1, the soap bar composition comprising about 10to about 20 weight percent water.
 9. The soap bar composition of claim8, the soap bar composition comprising about 12 to about 16 weightpercent water.
 10. The soap bar composition of claim 1, saidpolyalkylene glycol comprising a polyethylene glycol having a molecularweight in the range of about 300 to about
 800. 11. The soap barcomposition of claim 10, said polyethylene glycol comprising PEG-8. 12.The soap bar composition of claim 10, the soap bar compositioncomprising about 0.5 to about 5.0 weight percent polyethylene glycol.13. The soap bar composition of claim 12, the soap bar compositioncomprising about 1.0 to about 2.0 weight percent polyethylene glycol.14. The soap bar composition of claim 1, said free fatty acid having analkyl chain length with 8 to 22 carbon atoms.
 15. The soap barcomposition of claim 1, said free fatty acid comprising lauric acid. 16.The soap bar composition of claim 1, further comprising at least one oforganic salts, inorganic salts, chelating agents, vitamins, dyes,moisturizers, antibacterial agents, preservatives, antioxidants,conditioners, exfoliants, emollients, and sun screens.
 17. A process formaking soap bars having the following composition: a soap mixture; apolyethylene glycol having a molecular weight in the range of about 300to about 800; glycerin; water, and optionally, a free fatty acid, saidsoap bars exhibiting translucent properties, said process comprising:saponifying oils with a caustic solution to form a soap blend;optionally, neutralizing unreacted caustic solution with said free fattyacid; spray drying said soap blend to form soap pellets; adding saidpolyethylene glycol to said soap pellets; subjecting said soap pelletsto plodding, roll-milling and extrusion to form a soap ribbon; andcutting and stamping said soap ribbon to form soap bars.
 18. The processof claim 17, said soap mixture comprising soaps having alkyl chainlengths with 12 to 18 carbon atoms.
 19. The process of claim 17, saidsoap mixture comprising at least one of sodium tallowate, sodiumpalmitate, sodium stearate and sodium palm kernelate.
 20. The process ofclaim 17, the soap bars comprising about 65 to about 85 weight percentsoap mixture.
 21. The process of claim 20, the soap bars comprisingabout 70 to about 75 weight percent soap mixture.
 22. The process ofclaim 17, the soap bars comprising about 4.5 to about 8.5 weight percentglycerin.
 23. The process of claim 17, the soap bars comprising about6.0 to about 8.0 weight percent glycerin.
 24. The process of claim 17,the soap bars comprising about 10 to about 20 weight percent water. 25.The process of claim 24, the soap bars comprising about 12 to about 16weight percent water.
 26. The process of claim 17, said polyethyleneglycol comprising PEG-8.
 27. The process of claim 17, the soap barscomprising about 0.5 to about 5.0 weight percent polyethylene glycol.28. The process of claim 27, the soap bars comprising about 1.0 to about2.0 weight percent polyethylene glycol.
 29. The process of claim 17,said free fatty acid having an alkyl chain length with 8 to 22 carbonatoms.
 30. The process of claim 17, said free fatty acid comprisinglauric acid.
 31. The process of claim 17, further comprising adding tosaid soap pellets at least one of vitamins, dyes, moisturizers,antibacterial agents, antioxidants, conditioners, exfoliants,emollients, and sun screens.
 32. The process of claim 17, furthercomprising adding to said soap blend at least one of preservatives,chelating agents, organic salts and inorganic salts.
 33. A translucentsoap bar comprising, by weight: about 65 to about 80% of a soap mixture;about 0.5 to about 5.0% of a polyethylene glycol having a molecularweight in the range of about 300 to about 800; about 4.5 to about 8.5%glycerin; about 12 to about 16% water, and optionally, about 1.5 toabout 3.0% of a free fatty acid.
 34. The translucent soap bar of claim33. said soap mixture comprising at least one of sodium tallowate,sodium palmitate, sodium stearate and sodium palm kernelate.
 35. Thetranslucent soap bar of claim 33, the translucent soap bar comprisingabout 70 to about 75% soap mixture.
 36. The translucent soap bar ofclaim 33, the translucent soap bar comprising about 6.0 to about 8.0%glycerin.
 37. The translucent soap bar of claim 33, said polyethyleneglycol comprising PEG-8.
 38. The translucent soap bar of claim 33, thetranslucent soap bar comprising about 1.0 to about 2.0% polyethyleneglycol.
 39. The translucent soap bar of claim 33, said free fatty acidhaving an alkyl chain length with 8 to 22 carbon atoms.
 40. Thetranslucent soap bar of claim 39, said free fatty acid comprising lauricacid.